Steam Deck OLED - Dead (not turning on) after repasting the APU

No fans, no post, no bios, pulsing led light

- Introduction & explanation -

Hey guys, so I just got my steam deck on Friday and today Monday I decided to do a repaste on it because apparently the Noctua NT-H1 was supposed to give the deck a few degrees less and give better performance compared to the stock paste, so turn it off and unscrew the back, I remove the heat shield and disconnect the battery, disconnect the fan and take the fan and heatsink off carefully then clean with pure isopropyl alcohol, I put a pea amount on it then screw everything together very carefully.

- Experience & storage mode -

I work with tech repair and have been for years now, I just changed the bumper on an lcd deck a few hours before which worked fine and I’ve repaired countless of smartphones and laptops, I’ve changed thermal paste many times so my experience tells me I didn’t make a mistake while taking it apart, now I read somewhere that you’re supposed to put the battery in some kind of storage mode first, I didn’t know that as that is literally the first time I’m hearing about this on a device.

- Current state & diagnostics -

Anyhow… I now have a €679 piece of junk that doesn’t turn on, all it does is flash the led 3 times when pressing power (twice slowly then once faster), I tried while connected to AC and same but while connected to AC it has a constant light on at least. It does charge because now the light is green but still not booting.

- Tried solutions (plugged & unplugged)

Great let’s get to all the stuff I tried, there’s a lot… a lot.

1. Press power button

2. Hold power button for 10 second (20, 30, 60+ too)

3. Hold vol up and press power (to boot into BIOS)

4. Hold vol down and press power

5. Hold vol down + “…” and press power

6. Hold vol down + “…” and hold power (all different durations)

7. Hold vol down and “…” while plugged then unplug

8. Hold steam and press power

9. Press power 3 times quickly

10. Hold power 10 seconds then press power

- disassembly time -

11. Press power while battery disconnected while plugged

12. Hold power while battery disconnected while plugged

13. Press power after reconnecting battery (does nothing unless holding or plugging to ac

14. Hold power after reconnecting battery

15. Plug into ac after reconnecting battery (then doing all of the above)

16. Try to boot without heat sink

17. Try to boot without thermal paste

18. Reapplication of thermal paste

19. Taking the mobo out by disconnecting all flex cables and unscrewing it then reseating the mobo

20. Let it sit for 10-20 minutes plugged without touching it

21. Let it sit for 10-20 minutes unplugged without touching it

22. Trying to power without heat shield

- Things that did something -

1. Before even starting the repair I started unscrewing the back while it was still on and the speakers made a weird crackling/static noise, I then powered it off then the sound stopped. Then I went on with the repair.

2. First time I did number 7 the led went through some flashes of white and flashed blue once before turning back off… idc why this only did that first time, as far as I know this is a way to put the battery in storage mode and the blue light indicates that it works, but it hasn't done it since the first time

3. After spamming the power button and holding it then pressing random times, it flashed red 3 times, haven't been able to replicate…

- Things I will try next -

1. Let it stay plugged for hours with the battery disconnected then power on

2. Let it stay plugged for hours with the battery disconnected then power on

3. press power and let it stay plugged for hours with battery connected

4. press power and let it stay unplugged for hours with battery connected

5. Let it discharge by itself then power on

6. What ever crazy ideas you guys have that doesn’t void the warranty.

- Theory -

I have read someone’s comment here on a Reddit post about the same issue saying it has to do with the embedded controller (EC) that is bugged and thinks that there’s no battery charge and therefore won’t let me turn on.

Someone claims it’s a bug with the bios, I can’t be sure as I can’t boot into bios and see my ver